Astronomers discovered the smallest white dwarf ZTF J190132.9 + 145808.7, which is at the same time the most massive of all known stars of this type. This unusual object, by weight of 1.32-1.36 times the superior sun and the size compared with the moon, was formed during the confluence of two less massive white dwarfs. This is reported in an article published in the journal Nature.
The discovery was committed by scientists of the Palomar Observatory of the California Institute of Technology. More massive dwarfs always have smaller sizes, since nuclear combustion does not occur in their depths, and their size is regulated by quantum effects. The greater the White Dwarf, the more gravitational forces and the greater the pressure in the depths of the extinct star to balance them. The pressure creates a degenerate electronic gas – matter, consisting of electrons that cannot occupy the same quantum state (this is called the principle of Paul’s ban).
Researchers studied ZTF J1901 + 1458 object using a 5-meter Haile telescope. White dwarf rotates at a high speed with a period of 6.94 minutes, which is very unusual for them – usually one turn around for several hours. The spectroscope in the bracket observatory (Hawaii) showed the presence of an extreme magnetic field with an induction of 800 million GAuss, which is almost in a billion times the magnetic field at the Sun.
With an extreme density achieved in the center of ZTF J1901 + 1458, the kernel of certain elements may be subjected to an inverse beta decay, which is also called electronic gripping. In this case, electrons are removed, which contribute to the pressure of the degenerate gas, holding the star from the collapse. After several million years, heavy elements will be devastated to the kernel, as a result of which the star starts to shrink, the nuclear burning of oxygen will begin, and the supernova will break up with the formation of a neutron star.
If the hypothesis of the formation of neutron stars is correct, it may mean that a significant part of other neutron stars is formed in this way. A variety of star systems consisting of two white dwarfs are known. In the end, they merge, forming a massive white dwarf, which is destined to cholerate.